The use of a pair of elongated tubes which reciprocate relative to each other to perform cutting operation in vitreous surgery is known. O'Malley and Heintz, U.S. Pat. No. 3,815,604 dated June 11, 1974, shows a cutting instrument for use in vitreous surgery in which the inner tube reciprocates in the direction of the longitudinal axis of the tubes. As the end of the inner tube reciprocates across a window in the elongated tube, the shearing action is performed. O'Malley teaches that the cutting action of the instrument is enhanced by the use of a flared inner member to maintain a snug fit between the two tubular members. Others including Seiler, U.S. Pat. No. 4,011,869 dated Mar. 15, 1977, have addressed the problem of close machining tolerances and the friction that is created between the two tubular members of the O'Malley instrument in the reciprocating operation of the inner tube.
A surgical cutting instrument of the type disclosed by O'Malley and others should be easily handled by the person performing the surgery, should be strong in compression along its elongated axis, should be capable of avoiding non-elastic bending along its longitudinal axis, should be efficient in the reciprocational action of its inner parts, and effective in performing the desired internal surgery. The instrument of the present invention is directed to all of these needs.
A trend in surgical practices has been toward the use of instruments that will be disposable after a single use. Such a trend has increased the expenses in performing surgery that uses such instruments because of the one time use of the instruments. An instrument used one time should be constructed with the same care and precision as an instrument that will have several uses so the user frequently pays as much for the single use instrument as the multiple use instrument. When the instrument is destroyed after a single use, the equipment portion of the expense of the surgery must have been increased. In some cases the cost of a disposable instrument is kept within reason by reducing the material costs and the construction costs. Where instruments are to have more than a single use there is a reason to construct the instrument with more attention to the life of the materials used in the construction and a reason to give more attention to the wear induced frictions within the instrument. The surgical instrument of the present invention is designed with particular attention to the possibilities of more than a single use and with attention to the materials that will reduce friction and maintain cutting efficiency through several uses of the instrument.
It is an object of the present invention to provide a tubular microsurgery cutting apparatus that includes an inner and an outer tubular member with the inner member constructed in a form that reduces the friction between the inner and outer tubular members as the inner tube is reciprocated within the outer tube.
A further object of the present invention in accord with the preceding object is to provide an inner tubular sleeve that maintains efficient cutting engagement between the inner sleeve and outer tubular member while reducing the friction between the inner sleeve and outer tubular member during reciprocation of the inner sleeve within the outer tube.
A further object in accord with the preceding objects is an inner tubular sleeve provided with an expanded diameter at its cutting edge and with a construction that maintains the expanded diameter portion in working contact with the inside surface of the outer tubular member.
A further object in accord with the preceding objects is a tubular microsurgery cutting apparatus including an inner tubular sleeve with a spiral slot construction axially along the sleeve.
Further objects and features of the present invention will be readily apparent to those skilled in the art from the appended drawings and specification illustrating preferred embodiments wherein: